The work is designed to test the hypothesis that the shape and accommodative power of the lens is determined by the types, quantities and distribution of cytoplasmic filaments, namely the 5.0-8.0 nm actin and 9-12 nm intermediate filaments. As a corollary, disruption, or rearrangement of the normal pattern or change in density of filaments may result in loss of accommodation and/or development of cataract. Indeed, previous studies have shown a qualitative difference in the pattern of filaments in the cells of lenses with little or no accommodative capacity vs. those of lenses with some accommodative capacity. Furthermore, the lens cells of older members of a species generally appear to contain more cytoplasmic filaments than those of younger members. The new studies will be directed towards quantitation of the two types of filaments in young and old members of a species, and in members of several species representing the gamut of accommodative capacity. The main thrust of quantitation will be with electron microscopy techniques designed to differentiate between the two types of filaments, using two published methods, to enhance visualization of the polarity of actin filaments, and to identify actin filaments by an innovative method. Quantitation of actin in lenses of different species and ages by biochemical means will be attempted by DNAase I binding to actin on affinity chromatography columns.